Android Framework学习笔记 -- Surface的绘制过程

今天看到一篇很不错的的关于SurfaceFlinger的文章，主要是看到android源码中有一个简单明了的test，而且还被我编译过了，都不知道的前几个星期看的都是些什么东西- -
http://blog.csdn.net/jinzhuojun/article/details/17427491

还是从test开始看起吧
test的在工程中的位置:frameworks/native/services/surfaceflinger/tests/resize,用于在屏幕上显示一块色块

int main(int argc, char** argv){    // set up the thread-pool    sp<ProcessState> proc(ProcessState::self());    ProcessState::self()->startThreadPool();    // 连接到surfaceflinger    sp<SurfaceComposerClient> client = new SurfaceComposerClient();        // 创建surface    sp<SurfaceControl> surfaceControl = client->createSurface(String8("resize"),600, 800, PIXEL_FORMAT_RGB_565, 0);    sp<Surface> surface = surfaceControl->getSurface();        // 设置Layer的z轴    SurfaceComposerClient::openGlobalTransaction();    surfaceControl->setLayer(100000);    SurfaceComposerClient::closeGlobalTransaction();        // 操纵Buffer中内容    ANativeWindow_Buffer outBuffer;    surface->lock(&outBuffer, NULL);    ssize_t bpr = outBuffer.stride * bytesPerPixel(outBuffer.format);    android_memset16((uint16_t*)outBuffer.bits, 0xffff, bpr*outBuffer.height);    surface->unlockAndPost();    IPCThreadState::self()->joinThreadPool();    return 0;}

连接到surfaceflinger

补充一点，ComposerSerivce创建时会调用getSerivce函数，然后再调用defaultServiceManager获取ServiceManager接口IServiceManager，再通过IServiceManager的getService获取到SurfaceFlinger服务的接口，ISurfaceComposer其实就是SurfaceFlinger的代理接口。

创建surface

补充：Layer继承至SurfaceFlingerConsumer::ContentsChangedListener,实现了Listener的几个处理函数

• onFrameAvailable(const BufferItem& item)
• onFrameReplaced(const BufferItem& item)
• onSidebandStreamChanged()

设置Layer的z轴

使用openGlobaleTransaction可以将几个事务合并成一个提交,而且是必须的：

All composer parameters must be changed within a transaction
several surfaces can be updated in one transaction, all changes are
committed at once when the transaction is closed.
closeGlobalTransaction() requires an IPC with the server.

setLayer调用了SurfaceComposer的setLayer,与SurfaceFlinger的连接有点问题

操纵Buffer中的内容

其中BufferQueueProducer在queuebuffer中调用了BufferQueueCore的frameAvailableListener的onFrameAvailable方法，经过了一长串的调用最终会调用到Layer的onFrameAvailable。

下面是分析:
类图： 看了半天的surface post后消息的传递，重重的继承，各种set，（╯－＿－）╯╧╧
先写个大概流程，免得待会忘了
首先是consumer的创建 在Layer::onFirstRef()

sp<IGraphicBufferConsumer> consumer;BufferQueue::createBufferQueue(&producer, &consumer);

listener的创建 没错，mSurfaceFlingerConsumer就是个listener

mSurfaceFlingerConsumer = new SurfaceFlingerConsumer(consumer, mTextureName);

SuffaceFlingerComsumer的构造函数 call call call到了… ConsumerBase::ConsumerBase proxy是ConsumerBase自身的代理

status_t err = mConsumer->consumerConnect(proxy, controlledByApp);

Bp端的调用，Bn端的实现 在BufferQueueConsumer::consumerConnect,在这里做了个转发，而且还在h文件里，搞得cpp文件都没有consumerConnect，我&*&^%!(@

virtual status_t consumerConnect(const sp<IConsumerListener>& consumer,bool controlledByApp) {    return connect(consumer, controlledByApp);}

connect的实现

mCore->mConsumerListener = consumerListener;

也就是说

consumerListener == ConsumerBase == SuffaceFlingerComsumer

而下面又有

mSurfaceFlingerConsumer->setContentsChangedListener(this);

相当于

mCore->mConsumerListener == layer

所以queue的时候

listener.xxx == layer.onXXX;

从这以后，渲染工作就交给了SurfaceFlinger服务了